Crustal structure in the Campanian region (Southern Apennines, Italy) from potential field modelling

Y Kelemework,M Milano,M Fedi,M La Manna,G De Alteriis,M Iorio

doi:10.1038/s41598-021-93945-8

Abstract

We present a 3D model of the main crustal boundaries beneath the Campanian region and the onshore and offshore surrounding areas, based on high-resolution potential field data. Our main objective is the definition of the main structural interfaces in the whole Campanian region from gravity and magnetic data, thanks to their ability to define them on a regional and continuous way. The complex morphology of the Mesozoic carbonate platform, which is fundamental to constrain the top of geothermal reservoir, was reconstructed by inverting the vertical gradient of gravity. We assumed local information from seismic models and boreholes to improve the model. We modeled the deep crustal structures by spectral analysis of Bouguer gravity and magnetic data. The inferred depth estimates indicate a shallow crystalline basement below the Tyrrhenian crust and the Apulian foreland and a significant depression beneath the Bradanic foredeep. The map of the Moho boundary shows a NE-SE verging trough below the Southern Apennine chain and two pronounced uplifts beneath the foreland and the Tyrrhenian crust. We also estimated the depth to the magnetic bottom, showing a thick magnetic crust below the mountain chain and shallow depths where the crustal heat flow is high. The models were compared with seismic sections along selected profiles; a good agreement was observed, despite of some inherent lower resolution for the gravity modelling from spectral methods. The regional covering and the continuity of our estimated crustal interfaces make it a new and valid reference for further geological, geophysical and geothermal studies, especially in areas such as northern and eastern Campania, where there is an incomplete geophysical and geological information.

Highlights

The Apennine chain, linking the western Alps to the Maghrebian orogen, is one of the main orogenic belts of the central Mediterranean, resulting from the collisional events between the African and the European plates, which took place since the late Mesozoic-Cenozoic Alpine o rogeny[1,2,3]
This limitation can be well complemented by gravity data, which we find to be more suitable to model the crystalline basement top in regions affected by volcanism and intrusive bodies/dikes[17]
In this study we have shown that potential fields methods may represent an insightful and necessary tool to image of the subsurface geology, especially where direct information or other geophysical information is lacking

Summary

Introduction

The Apennine chain, linking the western Alps to the Maghrebian orogen, is one of the main orogenic belts of the central Mediterranean, resulting from the collisional events between the African and the European plates, which took place since the late Mesozoic-Cenozoic Alpine o rogeny[1,2,3]. The best advantage of potential field modelling with respect to seismic is ensuring a wide areal coverage, so yielding lateral continuity to the subsurface m odels[17] Within this framework, the purpose of this paper is providing new models of the Mesozoic carbonate platform, crystalline basement, Moho boundary and magnetic bottom beneath the Southern Apennines orogen. The extensional Tyrrhenian basin located between Sardinia, Sicily and Peninsular Italy is characterized by partly oceanic and thinned continental crust with an irregular seafloor[2,3,22,23,33,34] It represents a back-arc extensional feature developed at the rear of the Apennine system in late- and post-Tortonian times. The periTyrrhenian margin has undergone extensional tectonics during Plio-Quaternary accompanied by magma up rise and partly still active volcanism recognizable both at sea and onshore ( see[35] for a comprehensive review)

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Conclusion